Anti-peeping film and method for manufacturing same, and backlight module and display apparatus

ABSTRACT

A privacy protection film, a manufacturing method thereof, a backlight module, and a display device are provided. The privacy protection film includes a substrate, a light incident surface of the substrate is provided with a reflective layer, light transmission holes are provided on the reflective layer; a light exiting surface of the substrate is provided with a micro-lens array; each of the light transmission holes corresponds to at least one micro-lens in the micro-lens array; and the micro-lens is configured to control an exiting direction of light exiting from the light exiting surface of the substrate to remain unchanged; or, the micro-lens is configured to control an exiting direction of the light exiting from the light exiting surface of the substrate to be deflected toward a direction of an axis of the micro-lens.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese patent applicationNo. 201810327381.2 entitled “A PRIVACY PROTECTION FILM, MANUFACTURINGMETHOD THEREOF, BACKLIGHT MODULE, AND DISPLAY DEVICE” and filed withCNIPA on Apr. 12, 2018, the disclosure of which is incorporated hereinby reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to a privacy protectionfilm, a manufacturing method thereof, a backlight module, and a displaydevice.

BACKGROUND

A privacy protection film has a limited visible area, so that when adisplay device employing a privacy protection film is displaying,information being displayed on the display screen of the display devicecan be only read by a user from the front side, and cannot be seen byother people on a lateral side of the user. That is, others can only seea dark screen, which effectively protects the user's confidentialityand/or personal privacy.

SUMMARY

Embodiments of the present disclosure provide a privacy protection film,a manufacturing method thereof, a backlight module, and a displaydevice.

At least one embodiment provides a privacy protection film, comprising,a substrate. A light incident surface of the substrate is provided witha reflective layer; light transmission holes are provided on thereflective layer; a light exiting surface of the substrate is providedwith a micro-lens array; each of the light transmission holescorresponds to at least one micro-lens in the micro-lens array; and eachmicro-lens is configured to control an exiting direction of lightexiting from the light exiting surface of the substrate to remainunchanged; or, each micro-lens is configured to control an exitingdirection of the light exiting from the light exiting surface of thesubstrate to be deflected toward a direction of an axis of themicro-lens.

For example, in the micro-lens array, a distance p between axes of twoadjacent micro-lenses satisfies

${p \geq {2{t\left( {n^{2} - 1} \right)}^{\frac{1}{2}}}},$where n is a refractive index of the substrate, and t is a thickness ofthe substrate.

For example, a convexity correlation factor k of the micro-lenssatisfies

${k = {{\frac{h}{\left( {{t/\cos}\;\theta} \right)}\mspace{14mu}{and}\mspace{14mu} 1} \leq k \leq {1 + \frac{1}{n}}}},$where θ is a total reflection angle of the substrate and

${\theta = {\arcsin\left( \frac{1}{n} \right)}},$h is a distance from a vertex of the micro-lens to the reflective layer;and a viewing angle of the privacy protection film is inverselyproportional to the convex correlation factor k of the micro-lens.

For example, the light transmission holes comprise circular holes orpolygonal holes; a distance p′ between centers of two adjacent lighttransmission holes is equal to a distance p between axes of two adjacentmicro-lenses; and the axes of the micro-lenses are perpendicular to thelight incident surface of the substrate and pass through thecorresponding centers of the light transmission holes.

For example, a viewing angle correlation factor A of the privacyprotection film satisfies

${A = \frac{d}{p^{\prime}}},$where d is a diameter of each light transmission hole; and the viewingangle of the privacy protection film is proportional to the viewingangle correlation factor A.

For example, the micro-lens array has a shape of a hexagon, a square, ora rectangle; and each micro-lens has a shape of a spherical corona or anellipsoidal corona.

For example, a material of the substrate comprises polyethyleneterephthalate or polycarbonate; a material of the micro-lens is the sameas that of the substrate; or, a material of the micro-lens comprises anultraviolet curing adhesive or a photoresist.

At least one embodiment also provides a method of manufacturing theprivacy protection film, comprising: providing a substrate; forming areflective layer on the light incident surface of the substrate, andforming light transmission holes on the reflective layer; forming amicro-lens array on the light exiting surface of the substrate, so thateach of the light transmission holes corresponds to at least onemicro-lens in the micro-lens array. Each micro-lens is configured tocontrol the exiting direction of the light exiting from the lightexiting surface of the substrate to remain unchanged; or, eachmicro-lens is configured to control the exiting direction of the lightexiting from the light exiting surface of the substrate to be deflectedtoward the direction of the axis of the micro-lens.

At least one embodiment also provides a backlight module, comprising theprivacy protection film.

At least one embodiment also provides a display device, comprising thebacklight module.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will be described in more detailbelow with reference to accompanying drawings, so that those skilled inthe art can more clearly understand the embodiments of the presentdisclosure, in which:

FIG. 1 is a schematically perspective structural diagram illustrating aprivacy protection film according to an embodiment of the presentdisclosure;

FIG. 2 is a schematically cross-sectional structure diagram illustratinga privacy protection film according to an embodiment of the presentdisclosure;

FIG. 3(a) and FIG. 3(b) are schematic diagrams illustrating opticalsignal propagation of light exiting from a light transmission holerespectively in two different exiting directions according to anembodiment of the present disclosure;

FIG. 4(a), FIG. 4(b), and FIG. 4(c) are schematic diagrams illustratingthree different structures of a reflective layer in a privacy protectionfilm according to an embodiment of the present disclosure;

FIG. 5(a) is a graph illustrating light intensity effect of a privacyprotection film under different viewing angle correlation factors Aaccording to an embodiment of the present disclosure;

FIG. 5(b) is a graph illustrating light intensity effect of a privacyprotection film under different convexity correlation factors kaccording to an embodiment of the disclosure;

FIG. 6 is a schematically structural diagram illustrating a backlightmodule according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram illustrating privacy protection of adisplay device according to an embodiment of the present disclosure; and

FIG. 8 is a flowchart illustrating a method for manufacturing a privacyprotection film according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Technical solutions of the embodiments will be described in a clearlyand fully understandable way in connection with the drawings related tothe embodiments of the disclosure. It is apparent that the describedembodiments are a part but not all of the embodiments of the disclosure.Based on the described embodiments herein, one of ordinary skill in theart can obtain other embodiment(s), without any creative work, whichshall be within the scope of the disclosure.

Unless otherwise defined, all the technical and scientific terms usedherein have the same meanings as commonly understood by one of ordinaryskill in the art to which the present disclosure belongs. The terms,such as ‘first,’ ‘second,’ or the like, which are used in thedescription and the claims of the present disclosure, are not intendedto indicate any sequence, amount or importance, but for distinguishingvarious components. The terms, such as ‘comprise/comprising,’‘include/including,’ or the like are intended to specify that theelements or the objects stated before these terms encompass the elementsor the objects and equivalents thereof listed after these terms, but notpreclude other elements or objects. The terms, ‘on,’ ‘under,’ or thelike are only used to indicate relative position relationship, and whenthe absolute position of the object which is described is changed, therelative position relationship may be changed accordingly.

In a privacy protection film of an ultra-fine louver structure, aplurality of first resin strips are disposed in parallel on a substrateand a second resin strip is disposed between every two adjacent firstresin strips, wherein the first resin strips act as a transmission unit,the second resin strips act as an absorbing unit, and the first resinstrips have a different refractive index from that of the second resinstrips.

However, the inventors have discovered that although the second resinstrips in the privacy protection film can act as an absorption unit toabsorb light entering therein and block part of the lights passingthrough the privacy protection film, so as to limit the visible area ofthe privacy protection film and realize the privacy protection function,the second resin strips absorbing lights can also tend to cause anexcessively low light transmittance of the privacy protection film,reduce the intensity of the light exiting from the backlight modulewhere the privacy protection film is disposed, and have adverse effecton the display effect of the display device where the privacy protectionfilm is disposed. Moreover, the second resin strips and the first resinstrips are alternately disposed in parallel so that the privacyprotection film can only protect privacy in a plane perpendicular to therunning direction of the resin strips, which means that the privacyprotection film can protect privacy only in one plane, and it isimpossible to realize privacy protection in all directions.

In order to further explain the privacy protection film and themanufacturing method, the backlight module, and the display deviceaccording to embodiments of the present disclosure, detailed descriptionis given below with reference to the accompanying drawings.

Referring to FIG. 1 to FIG. 3(b), a privacy protection film according toan embodiment of the present disclosure includes a substrate 1, a lightincident surface of the substrate 1 is provided with a reflective layer3, light transmission holes 30 are provided on the reflective layer 3; alight exiting surface of the substrate 1 is provided with a micro-lensarray; each light transmission hole 30 corresponds to at least onemicro-lens 20 in the micro-lens array; each micro-lens 20 is configuredto control an exiting direction of light exiting from the light exitingsurface of the substrate 1 to remain unchanged; or, each micro-lens 20is configured to control the exiting direction of the light exiting fromthe light exiting surface of the substrate 1 to be deflected toward adirection of an axis of the micro-lens 20.

The substrate 1 is a transparent substrate, and uses a lighttransmitting resin material, for example, polyethylene terephthalate(PET), or polycarbonate (PC), or the like, and can has a thickness tabout 10 μm to about 200 μm. The light incident surface of the substrate1 refers to a surface of the substrate 1 facing a backlight source, thatis, a surface of the substrate 1 where light exiting from the backlightsource enters the substrate 1. The light exiting surface of thesubstrate 1 refers to a surface of the substrate 1 facing away from thebacklight source, that is, a surface of the substrate 1 where lightexiting from the backlight source exits from the substrate 1 afterpassing through the substrate 1.

When the privacy protection film according to the above embodiment isused in conjunction with a backlight source, the light exiting from thebacklight source illuminates the reflective layer 3 of the privacyprotection film. The light beams exiting from the backlight source arein a Lambertian distribution. After the light beams exiting from thebacklight source enter the substrate 1 through the light transmissionholes 30 of the layer 3, under the refraction of the substrate 1, thelight beams exiting from the backlight source will be concentrated to asmall three-dimensional cone angle in a corresponding area inside thesubstrate 1, and exit from the light exiting surface of the substrate 1at the three-dimensional cone angle. Then, for the light beams exitingfrom the light exiting surface of the substrate 1, each micro-lenses 20provided on the light exiting surface of the substrate 1 is configuredto control the light path, so that the light exiting direction of eachlight beam exiting from the light exiting surface of the substrate 1remains unchanged, as shown in FIG. 3(a), or, the light exitingdirection from the light exiting surface of the substrate 1 is deflectedtoward the direction of the axis of the corresponding micro-lens 20, asshown in FIG. 3(b). It can enable the light beams exiting from thebacklight source to exit at the three-dimensional cone angle afterpassing through the privacy protection film and to keep a relativelysmall exiting angle, to effectively limit the viewing angle of thedisplay device where the privacy protection film is disposed, so as toachieve privacy protection of the display device in all directions. Thatis, the privacy protection function of the display device is not limitedto one plane, and except for the user who is directly opposite thedisplay device, other people around the user cannot see the displaycontent of the display device.

In addition, the privacy protection film according to this embodimentcan use the reflective layer 3 provided on the light incident surface ofthe substrate 1 to reflect light beams of the backlight source which donot enter the light transmission holes 30, back to the interior of thebacklight source, so that this part of light beams can be emitted to thelight transmission holes 30 again after being scattered, refracted, orreflected by other optical components in the backlight module. This cannot only improve the utilization rate of the lights emitted by thebacklight source, but also can improve the intensity of the lightexiting from the backlight module where the privacy protection film isdisposed, to realize high-brightness display of the display device.

It can be understood that the axis of each micro-lens 20 generallyrefers to the optical axis 21 of the micro-lens 20. To permit the lightexiting from the light exiting surface of the substrate 1 to keep theexiting direction unchanged or have its exiting direction deflectedtoward the direction of the axis of each micro-lens 20 after passingthrough the micro-lens 20, the micro-lenses 20 should have a samerefractive index as that of the substrate 1. Therefore, the micro-lens20 can be made of a same material as that of the substrate 1, or can bemade of an ultraviolet curing adhesive or a photoresist material,similar to that of the material of the substrate. In addition, themicro-lens array can have a shape of a hexagon, a square, or arectangle, and each of the micro-lenses 20 in the micro-lens array canbe a curved shape, such as a spherical corona, or an ellipsoidal corona,but the embodiments of the present disclosure are not limited thereto.

The count of the light transmission holes 30 can be designed accordingto requirements; and the shape of each light transmission hole 30 can becircular, or polygonal, for example, a geometrically symmetrical shape.In this embodiment, an array of light transmission holes is provided onthe reflective layer 3, and the array of light transmission holes canhave a shape match that of the micro-lens array.

To more clearly illustrate the structure of the privacy protection filmand the privacy protection effect thereof in this embodiment, forexample, referring to FIG. 2 , when a distance p between centers of twoadjacent light transmission holes 30 is equal to a distance p betweenaxes of two adjacent micro-lenses 20, that is, the light transmissionholes 30 correspond to the micro-lenses 20 one to one, the axis of eachmicro-lens 20 is perpendicular to the light incident surface of thesubstrate 1 and passes through the center of the corresponding lighttransmission hole 30. The light transmission hole 30 has a diameter d,and a viewing angle correlation factor A of the privacy protection filmsatisfies

$A = {\frac{d}{p^{\prime}}.}$The viewing angle of the privacy protection film is proportional to theviewing angle correlation factor A; that is, the smaller the viewingangle correlation factor A is, the narrower the distribution of thelight intensity exiting from the privacy protection film through thelight transmission holes 30 is. The smaller the viewing angle of theprivacy protection film is, the better the privacy protection effect ofthe privacy protection film is. FIG. 5(a) can be referred for details ofa graph of light intensity effect of a privacy protection film underdifferent values of A.

Continuously referring to FIG. 2 , when the refractive index of thesubstrate 1 is n, and the thickness of the substrate 1 is t, thedistance p between axes of two adjacent micro-lenses 20 in themicro-lens array can be obtained according to a formula

$p \geq {2{{t\left( {n^{2} - 1} \right)}^{\frac{1}{2}}.}}$The total reflection angle of the substrate 1 is related to itsrefractive index n, and when the total reflection angle of the substrate1 is θ

$\theta = {{\arcsin\left( \frac{1}{n} \right)}.}$A distance from the apex of each micro-lens 20 to the reflective layer 3is h. A convexity correlation factor k of the micro-lens 20 can beobtained according to a formula:

${k = {\frac{h}{\left( {{t/\cos}\;\theta} \right)} = \frac{h}{r}}},$and the value of the convexity correlation factor k satisfies

${1 \leq k \leq {1 + \frac{1}{n}}};$where when k=1, the light beams exiting from the light exiting surfaceof the substrate 1 can keep the exiting directions unchanged under thecontrol of the micro-lens 20; and when

${k = {1 + \frac{1}{n}}},$the light beams exiting from the light exiting surface of the substrate1 can be deflected toward the direction of the axis of each micro-lens20 under the control of the micro-lens 20; r=t/cos θ, where r is acritical dimension that the light beams entering the substrate 1 fromthe light transmission hole 30 can exit from the light exiting surfaceof the substrate 1. The viewing angle of the privacy protection film isinversely proportional to the convexity correlation factor k of eachmicro-lens 20, that is, the larger the value of the convexitycorrelation factor k of the micro-lens 20 is, the more convex themicro-lens 20 is, so that the narrower the distribution of the lightintensity exiting from the micro-lens 20 is, the smaller the viewingangle of the privacy protection film is, and the better the privacyprotection effect of the privacy protection film is. FIG. 5(b) can bereferred for details of a graph of light intensity effect of a privacyprotection film under different values of k.

It is to be additionally noted that although the viewing angle of theprivacy protection film can decrease as the value of the viewing anglecorrelation factor A decreases, a decrease in the value of the viewingangle correlation factor A will also cause a decrease in the intensitiesof lights exiting from the privacy protection film. In this way, thestructural design of the privacy protection film needs to consider thevalues of the viewing angle correlation factor A and the convexitycorrelation factor k of the micro-lenses 20 in order to ensure orimprove the light intensity of the backlight module while achievingbetter privacy protection performance.

It is to be noted that, in the above embodiment, the reflective layer 3can adopt a film structure having a high reflectance, such as a silvercoating layer, an aluminum coating layer, or a silver-aluminum compositelayer. The thickness of the reflective layer 3 can be designedindependently as required, such as a thin film shown in FIG. 4(a), or areflective film with a thickness of 20 μm to 200 μm as shown in FIGS.4(b) and 4(c). As an example, the reflective layer 3 is a reflectivefilm material with a certain thickness, and the light transmission hole30 provided on the reflective layer 3 is a cylindrical hole withconstant radial dimensions or a circular truncated cone hole with agradually changing radial dimension.

In the privacy protection film according to the above embodiment, whenthe light beams exiting from the backlight source illuminate thereflective layer of the privacy protection film, the light beams exitingfrom the backlight source are in a Lambertian distribution. After lightexiting from the backlight source enters the substrate through a lighttransmission hole of the layer, under the refraction of the substrate,the light beams exiting from the backlight source will be concentratedto a small three-dimensional cone angle in a corresponding area insidethe substrate, and exit from the light exiting surface of the substrateat the three-dimensional cone angle. Then, for the light beams exitingfrom the light exiting surface of the substrate, the micro-lensesprovided on the light exiting surface of the substrate are configured tocontrol the light paths, so that the light exiting directions of thelight beams exiting from the light exiting surface of the substrateremain unchanged, or, the light exiting directions from the lightexiting surface of the substrate are deflected toward the direction ofthe axis of the corresponding micro-lens. It can allow the light beamsexiting from the backlight source exit at the three-dimensional coneangle after passing through the privacy protection film and keeprelatively small exiting angles, to effectively limit the viewing angleof the display device where the privacy protection film is disposed, soas to achieve privacy protection of the display device in alldirections.

Moreover, the privacy protection film according to the embodiment of thepresent disclosure can use the reflective layer provided on the lightincident surface of the substrate to reflect light beams of thebacklight source which do not enter the light transmission holes, backto the interior of the backlight source, so that this part of lightbeams can be emitted to the light transmission holes again after beingscattered, refracted, or reflected by other optical components in thebacklight module. In this way, the utilization rate of the lightsemitted by the backlight source is improved, and the intensity of thelight exiting from the backlight module where the privacy protectionfilm is disposed is also improved, so that a high-brightness display ofthe display device is realized.

An embodiment of the present disclosure also provides a method ofmanufacturing a privacy protection film, which is used to manufacturethe privacy protection film according to the above embodiment. As shownin FIG. 8 , the manufacturing method includes the following operations.

S10, a substrate is provided.

As an example, a light transmissive resin material, such as polyethyleneterephthalate (PET), or polycarbonate (PC), is used to form a substratewith a thickness of 10 μm to 200 μm.

S20, a reflective layer is formed on the light incident surface of thesubstrate, and light transmission holes are formed on the reflectivelayer.

The light incident surface of the substrate refers to a surface of thesubstrate facing the backlight source, that is, a surface from which thelight exiting from the backlight source enters the substrate. The lightincident surface of the substrate can be made of a material with a highreflectivity, such as silver, or aluminum, to form a reflective layer.When the light transmission holes are formed in the reflective layer,the count of the light transmission holes can be designed as required.The shape of the light transmission hole can be circular or polygonal,for example, a geometrically symmetrical shape. In this embodiment, anarray of light transmission holes is provided on the reflective layer.The shape of the array of light transmission holes can be hexagonal,square, or rectangular, but the embodiments of the present disclosureare not limited thereto.

S30, a micro-lens array is formed on the light exiting surface of thesubstrate, so that each light transmission hole corresponds to at leastone micro-lens in the micro-lens array; each micro-lens is configured tocontrol the exiting direction of the light exiting from the lightexiting surface of the substrate to remain unchanged; or, eachmicro-lens is configured to control the exiting direction of the lightexiting from the light exiting surface of the substrate to be deflectedtoward the direction of the axis of the micro-lens.

The light exiting surface of the substrate refers to a surface of thesubstrate facing away from the backlight source, that is, a surface ofthe substrate where the light exiting from the backlight source exitsthe substrate after passing through the substrate. The micro-lens arraycan have a shape of a hexagon, a square, or a rectangle, and eachmicro-lens in the micro-lens array can be a curved shape, such as aspherical corona, or an ellipsoidal corona, but the embodiments of thepresent disclosure are not limited thereto.

The axis of each micro-lens refers to the optical axis of themicro-lens. In order to enable the light exiting from the light exitingsurface of the substrate to keep the exiting direction unchanged or haveits exiting direction deflected toward the direction of the axis of themicro-lens after passing through the micro-lens, the micro-lenses have asame refractive index as that of the substrate. In this way, themicro-lenses can be made of a same material as that of the substrate, orcan be made of an ultraviolet curing adhesive or a photoresist, similarto the material of the substrate.

In the privacy protection film manufactured by the method herein, whenthe lights exiting from the backlight source illuminate the reflectivelayer of the privacy protection film, the lights exiting from thebacklight source are in a Lambertian distribution. After a light exitingfrom the backlight source enters the substrate through a lighttransmission hole of the layer, under the refraction of the substrate,the light beams exiting from the backlight source will be concentratedto a small three-dimensional cone angle in a corresponding area insidethe substrate, and exit from the light exiting surface of the substrateat the three-dimensional cone angle. Then, for the light beams exitingfrom the light exiting surface of the substrate, each micro-lensprovided on the light exiting surface of the substrate is configured tocontrol the light paths, so that the light exiting directions of thelight beams exiting from the light exiting surface of the substrateremain unchanged, or, the light exiting directions from the lightexiting surface of the substrate are deflected toward the direction ofthe axis of the corresponding micro-lens. It can ensure that the lightbeams exiting from the backlight source exit at the three-dimensionalcone angle after passing through the privacy protection film and keep arelatively small exiting angle, so that it can effectively limit theviewing angle of the display device where the privacy protection film isdisposed, so that the privacy protection of the display device in alldirections.

Moreover, the privacy protection film manufactured by the method hereincan use the reflective layer provided on the light incident surface ofthe substrate to reflect light beams of the backlight source which donot enter the light transmission holes, back to the interior of thebacklight source, so that this part of light beams can be emitted to thelight transmission holes again after being scattered, refracted, orreflected by other optical components in the backlight module. In thisway, the utilization rate of the lights emitted by the backlight sourcecan be improved, and the intensity of the light exiting from thebacklight module where the privacy protection film is disposed is alsoimproved, so that a high-brightness display of the display device isrealized.

An embodiment of the present disclosure also provides a backlightmodule. The backlight module includes a backlight source, a light guideplate, and various optical films including the privacy protection filmdescribed above. The backlight source, the light guide plate, and theoptical films can have a designed structure relationship. Exemplarily,as shown in FIG. 6 , the backlight module includes a backlight source 5,a reflective sheet 4, a light guide plate 6, a diffusion sheet 7, aprivacy protection film 8, and a sealant frame 9. The backlight source 5is disposed on a lateral side of the light guide plate 6. The reflectivesheet 4 is disposed on the light incident surface side of the lightguide plate 6, the diffusion sheet 7 and the privacy protection film 8are sequentially disposed on the light exiting surface side of the lightguide plate 6, and the sealant frame 9 surrounds the reflective sheet 4,the light guide plate 6, the diffusion sheet 7, and the privacyprotection film 8 to seal the gaps between the optical elements. Theprivacy protection film in the backlight module according to theembodiment of the present disclosure has the same advantages as theprivacy protection film in the above embodiments, which will not berepeated here.

An embodiment of the present disclosure also provides a display device,which includes the backlight module provided in the above embodiment.The backlight module in the display device according to the embodimentof the present disclosure has the same advantages as the backlightmodule in the above embodiment. Exemplarily, as shown in FIG. 7 , in thedisplay device 11 provided in the embodiment, the light beams exitingfrom the backlight module are emitted at a three-dimensional cone angle,and the exiting angle is kept small, so that the display device 11 candisplay content at a viewing angle 12 as shown in FIG. 7 . In this way,except for the user B who is directly opposite the display device 11,other people C around the user B cannot see the display content of thedisplay device 11, so as to achieve privacy protection of the displaydevice in all directions.

The display device provided in the above embodiment can be any productor component having a display function, such as a mobile phone, a tabletcomputer, a television, a display, a notebook computer, a digital photoframe, or a navigator.

The following statements should be noted:

(1) The accompanying drawings involve only the structure(s) inconnection with the embodiment(s) of the present disclosure, and otherstructure(s) can be referred to common design(s).

(2) For the purpose of clarity only, in the accompanying drawings forillustrating the embodiment(s) of the present disclosure, the thicknessof a layer or a region may be enlarged or reduced, that is, the figuresare not drawn according to the actual scale.

(3) Without conflicting with each other, the embodiments of the presentdisclosure and elements in the embodiments can be combined to obtain newembodiments, and these new embodiments shall fall within the scope ofthe present disclosure.

The description above is only exemplary embodiments of the presentdisclosure, and the scope of the present disclosure is not limitedthereto. Any changes or substitutions readily conceived by one ofordinary skill in the art without departing the technical scope of thepresent embodiments, shall fall within the scope of the presentdisclosure.

What is claimed is:
 1. A privacy protection film comprising, asubstrate, wherein a light incident surface of the substrate is providedwith a reflective layer; light transmission holes are provided on thereflective layer; a light exiting surface of the substrate is providedwith a micro-lens array; each of the light transmission holescorresponds to at least one micro-lens in the micro-lens array; eachmicro-lens is configured to control an exiting direction of lightexiting from the light exiting surface of the substrate to remainunchanged; or, each micro-lens is configured to control an exitingdirection of the light exiting from the light exiting surface of thesubstrate to be deflected toward a direction of an axis of themicro-lens; in the micro-lens array, a distance p between axes of twoadjacent micro-lenses satisfies${p \geq {2{t\left( {n^{2} - 1} \right)}^{\frac{1}{2}}}},$ where n is arefractive index of the substrate, and t is a thickness of thesubstrate; a convexity correlation factor k of the micro-lens satisfies${k = {{\frac{h}{\left( {{t/\cos}\;\theta} \right)}\mspace{14mu}{and}\mspace{14mu} 1} \leq k \leq {1 + \frac{1}{n}}}},$where θ is a total reflection angle of the substrate and${\theta = {\arcsin\left( \frac{1}{n} \right)}},$ h is a distance from avertex of the each micro-lens to the reflective layer; and a viewingangle of the privacy protection film is inversely proportional to theconvex correlation factor k of the micro-lens.
 2. The privacy protectionfilm according to claim 1, wherein the light transmission holes comprisecircular holes or polygonal holes; a distance p′ between centers of twoadjacent light transmission holes is equal to a distance p between axesof two adjacent micro-lenses; and the axes of the micro-lenses areperpendicular to the light incident surface of the substrate and passthrough the corresponding centers of the light transmission holes. 3.The privacy protection film according to claim 2, wherein a viewingangle correlation factor A of the privacy protection film satisfies${A = \frac{d}{p^{\prime}}},$ where d is a diameter of each lighttransmission hole; and the viewing angle of the privacy protection filmis proportional to the viewing angle correlation factor A.
 4. Theprivacy protection film according to claim 3, wherein a material of thesubstrate comprises polyethylene terephthalate or polycarbonate; amaterial of the micro-lens is the same as that of the substrate; or, amaterial of the micro-lens comprises an ultraviolet curing adhesive or aphotoresist.
 5. The privacy protection film according to claim 2,wherein a material of the substrate comprises polyethylene terephthalateor polycarbonate; a material of the micro-lens is the same as that ofthe substrate; or, a material of the micro-lens comprises an ultravioletcuring adhesive or a photoresist.
 6. The privacy protection filmaccording to claim 1, wherein the micro-lens array has a shape of ahexagon, a square, or a rectangle; and each micro-lens has a shape of aspherical corona or an ellipsoidal corona.
 7. The privacy protectionfilm according to claim 1, wherein a material of the substrate comprisespolyethylene terephthalate or polycarbonate; a material of themicro-lens is the same as that of the substrate; or, a material of themicro-lens comprises an ultraviolet curing adhesive or a photoresist. 8.A method of manufacturing the privacy protection film according to claim1, comprising: providing a substrate; forming a reflective layer on thelight incident surface of the substrate, and forming light transmissionholes on the reflective layer; forming a micro-lens array on the lightexiting surface of the substrate, so that each of the light transmissionholes corresponds to at least one micro-lens in the micro-lens array;wherein each micro-lens is configured to control the exiting directionof the light exiting from the light exiting surface of the substrate toremain unchanged; or, each micro-lens is configured to control theexiting direction of the light exiting from the light exiting surface ofthe substrate to be deflected toward the direction of the axis of themicro-lens.
 9. The privacy protection film according to claim 1, whereinthe light transmission holes comprise circular holes or polygonal holes;a distance p′ between centers of two adjacent light transmission holesis equal to a distance p between axes of two adjacent micro-lenses; andthe axes of the micro-lenses are perpendicular to the light incidentsurface of the substrate and pass through the corresponding centers ofthe light transmission holes.
 10. The privacy protection film accordingto claim 1, wherein the light transmission holes comprise circular holesor polygonal holes; a distance p′ between centers of two adjacent lighttransmission holes is equal to a distance p between axes of two adjacentmicro-lenses; and the axes of the micro-lenses are perpendicular to thelight incident surface of the substrate and pass through thecorresponding centers of the light transmission holes.
 11. The privacyprotection film according to claim 10, wherein a viewing anglecorrelation factor A of the privacy protection film satisfies${A = \frac{d}{p^{\prime}}},$ where d is a diameter of each lighttransmission hole; and the viewing angle of the privacy protection filmis proportional to the viewing angle correlation factor A.
 12. Theprivacy protection film according to claim 11, wherein the micro-lensarray has a shape of a hexagon, a square, or a rectangle; and eachmicro-lens has a shape of a spherical corona or an ellipsoidal corona.13. The privacy protection film according to claim 12, wherein amaterial of the substrate comprises polyethylene terephthalate orpolycarbonate; a material of the micro-lens is the same as that of thesubstrate; or, a material of the micro-lens comprises an ultravioletcuring adhesive or a photoresist.
 14. The privacy protection filmaccording to claim 1, wherein a material of the substrate comprisespolyethylene terephthalate or polycarbonate; a material of themicro-lens is the same as that of the substrate; or, a material of themicro-lens comprises an ultraviolet curing adhesive or a photoresist.15. The privacy protection film according to claim 1, wherein a materialof the substrate comprises polyethylene terephthalate or polycarbonate;a material of the micro-lens is the same as that of the substrate; or, amaterial of the micro-lens comprises an ultraviolet curing adhesive or aphotoresist.
 16. A backlight module, comprising a privacy protectionfilm, wherein the privacy protection film comprises: a substrate,wherein a light incident surface of the substrate is provided with areflective layer; light transmission holes are provided on thereflective layer; a light exiting surface of the substrate is providedwith a micro-lens array; each of the light transmission holescorresponds to at least one micro-lens in the micro-lens array; eachmicro-lens is configured to control an exiting direction of lightexiting from the light exiting surface of the substrate to remainunchanged; or, each micro-lens is configured to control an exitingdirection of the light exiting from the light exiting surface of thesubstrate to be deflected toward a direction of an axis of themicro-lens; in the micro-lens array, a distance p between axes of twoadjacent micro-lenses satisfies${p \geq {2{t\left( {n^{2} - 1} \right)}^{\frac{1}{2}}}},$ where n is arefractive index of the substrate, and t is a thickness of thesubstrate; a convexity correlation factor k of the micro-lens satisfies${k = {{\frac{h}{\left( {{t/\cos}\theta} \right)}{and}1} \leq k \leq {1 + \frac{1}{n}}}},$where θ is a total reflection angle of the substrate and${\theta = {\arcsin\left( \frac{1}{n} \right)}},$ h is a distance from avertex of the each micro-lens to the reflective layer; and a viewingangle of the privacy protection film is inversely proportional to theconvex correlation factor k of the micro-lens.
 17. A display device,comprising a backlight module, wherein the backlight module comprises: aprivacy protection film, wherein the privacy protection film comprises:a substrate, wherein a light incident surface of the substrate isprovided with a reflective layer; light transmission holes are providedon the reflective layer; a light exiting surface of the substrate isprovided with a micro-lens array; each of the light transmission holescorresponds to at least one micro-lens in the micro-lens array; eachmicro-lens is configured to control an exiting direction of lightexiting from the light exiting surface of the substrate to remainunchanged; or, each micro-lens is configured to control an exitingdirection of the light exiting from the light exiting surface of thesubstrate to be deflected toward a direction of an axis of themicro-lens; in the micro-lens array, a distance p between axes of twoadjacent micro-lenses satisfies${p \geq {2{t\left( {n^{2} - 1} \right)}^{\frac{1}{2}}}},$ where n is arefractive index of the substrate, and t is a thickness of thesubstrate; a convexity correlation factor k of the micro-lens satisfies${k = {{\frac{h}{\left( {{t/\cos}\theta} \right)}{and}1} \leq k \leq {1 + \frac{1}{n}}}},$where θ is a total refection angle of the substrate and${\theta = {\arcsin\left( \frac{1}{n} \right)}},$ h is a distance from avertex of the each micro-lens to the reflective layer; and a viewingangle of the privacy protection film is inversely proportional to theconvex correlation factor k of the micro-lens.